1. Field of the Present Invention
The present invention relates to a wiring substrate and a semiconductor device having a semiconductor element formed by a droplet discharging method typified by an inkjet method, and further manufacturing methods thereof.
2. Description of the Related Art
Conventionally, an active matrix driving type display panel or semiconductor integrated circuit including a semiconductor element typified by a thin film transistor (hereinafter, TFT) or a MOS transistor is formed by patterning each thin film with light-exposure process (hereinafter, a photolithography process) using a photomask.
In the photolithography process, resist is applied to a whole substrate, pre-baked, then the substrate is irradiated with ultraviolet rays or the like using a photomask and a resist pattern is formed by development. After that, a thin film existing outside a portion to be a film pattern or a wiring (a film of a semiconductor material, an insulator material, or a conductor material) is etch-removed with the resist pattern as a mask pattern for forming a film-pattern or a wiring.
Reference 1 (Japanese Patent Laid-Open No. 2000-188251) describes a technique for forming a film on a semiconductor wafer with an apparatus that can continuously discharge resist from its nozzle to have a linear shape with a small diameter so as to reduce loss of materials for forming films.
However, when forming a wiring or a film-pattern using a conventional photolithography process, almost all materials of the wiring or the film pattern and a resist material become wasted and the number of steps of forming the wiring or a mask pattern becomes large; therefore throughput is decreased.
A light-exposure apparatus used in the photolithography process has difficulty in exposing a large substrate to light at once. Accordingly, a manufacturing method of a semiconductor device using a large substrate needs a plurality of times of light-exposure, which leads to misalignment with an adjacent pattern and reduction in yield.
It is necessary to discharge a material solution whose droplet diameter is small in order to form a semiconductor element that is minute and occupies a small area by a droplet-discharging method. Reduction in diameter of the discharge opening is required to be small so as to discharge such a material solution. However, in this case, the tip of the discharge opening is clogged with the material solution because a composition of the material solution is attached thereto, dried or solidified therein, and thus it is difficult to discharge a constant amount of material solution continuously or stably. Consequently, there is a problem in that throughput or yield of a semiconductor device using the semiconductor element is reduced.